For many years, the scientific community has had a strong desire to develop a method for preserving biological specimens for future use without compromising the utility of the specimen. This has become increasingly important for clinical and scientific applications which include preservation of human oocytes, frozen quarantines of donor eggs to prevent transmission of infectious diseases, long-term storage of embryos, and other preservation of biologic materials.
Common methods for preserving biological specimens often involve freezing the specimens. While some freezing methods have been successful others have had less positive results. Problems associated with current freezing methods include the formation of ice crystals, which may injure the specimens due to the sharp edges of the crystals, and toxicity introduced into the specimen as a result of the use of cryopreservation agents.
Documents with some relevance to this subject include: U.S. Pat. No. 6,381,967 and U.S. Pat. No. 6,702,523.
U.S. Pat. No. 6,381,967 relates to a method and apparatus for hyper-rapid freezing of liquid samples by converting the samples into droplets and rapidly driving the droplets directly onto the surface of a solid or slushed refrigerant. It is desirable to be better able to control the velocity and acceleration of the droplets as they are driven on to a refrigerant target. If constant acceleration could be achieved, fragile liquid samples such as biological material or living cells would preserve their integrity as they would be subjected to relatively low gravitational forces.